package lemon.mvc.util;

import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.nio.charset.Charset;
import java.security.MessageDigest;

import lemon.mvc.mvc.exception.CodingException;

/**
 * 各种格式的编码加码工具类
 *
 * @author howsun(zjh@58.com)
 * @Date 2010-10-26
 * @version v0.1
 */
public abstract class CodingUtil {

    public static final String UTF8 = "UTF-8";
    public static final String UTF16 = "UTF-16";
    public static final String UTF16BE = "UTF-16BE";
    public static final String UTF16LE = "UTF-16LE";
    public static final String US_ASCII = "US-ASCII";
    public static final String ISO8859_1 = "ISO-8859-1";
    public static final Charset CHARSET_UTF8 = Charset.forName(UTF8);

    /**
     * 默认编码
     * @return String
     */
    public static String getDefaultEncoding() {
        return Charset.defaultCharset().name();
    }

    /**
     * MD5加密
     * @param origin
     * @return 加密后的结果
     */
    public static String MD5Encoding(String origin) {
        return MD5.MD5Encoding(origin);
    }

    /**
     * Base64编码
     * @param input
     * @return
     */
    public static String base64Encode(byte[] input) {
        return new String(Base64.encodeBase64(input));
    }

    /**
     * Base64编码, URL安全(将Base64中的URL非法字符如+,/=转为其他字符, 见RFC3548).
     * @param input
     * @return
     */
    public static String base64UrlSafeEncode(byte[] input) {
        return Base64.encodeBase64URLSafeString(input);
    }

    /**
     * Base64解码.
     * @param input
     * @return
     */
    public static byte[] base64Decode(String input) {
        return Base64.decodeBase64(input);
    }

    /**
     * URL 编码, Encode默认为UTF-8. 
     * @param input
     * @return
     */
    public static String urlEncode(String input) {
        try {
            return URLEncoder.encode(input, UTF8);
        } catch (UnsupportedEncodingException e) {
            throw new CodingException("Unsupported Encoding Exception", e);
        }
    }

    /**
     * URL 解码, Encode默认为UTF-8. 
     * @param input
     * @return
     */
    public static String urlDecode(String input) {
        try {
            return URLDecoder.decode(input, UTF8);
        } catch (UnsupportedEncodingException e) {
            throw new CodingException("Unsupported Encoding Exception", e);
        }
    }

    /**
     * Hex编码.
     * @param input
     * @return
     */
    public static String hexEncode(byte[] input) {
        return Hex.encodeHexString(input);
    }

    /**
     * Hex解码.
     * @param input
     * @return
     */
    public static byte[] hexDecode(String input) {
        try {
            return Hex.decodeHex(input.toCharArray());
        } catch (Exception e) {
            throw new CodingException("Hex Decoder exception", e);
        }
    }

    /**
     * Html 转码.
    
    public static String htmlEscape(String html) {
    	return StringEscapeUtils.escapeHtml(html);
    }
     */
    /**
     * Html 解码.
    
    public static String htmlUnescape(String htmlEscaped) {
    	return StringEscapeUtils.unescapeHtml(htmlEscaped);
    }
     */

    /**
     * Xml 转码.
    
    public static String xmlEscape(String xml) {
    	return StringEscapeUtils.escapeXml(xml);
    }
     */
    /**
     * Xml 解码.
    
    public static String xmlUnescape(String xmlEscaped) {
    	return StringEscapeUtils.unescapeXml(xmlEscaped);
    }
     */

    /**
     * MD5加密算法
     */
    static class MD5 {

        private static final String[] hexDigits = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };
        private static MessageDigest md;

        static {
            try {
                md = MessageDigest.getInstance("MD5");
            } catch (Exception e) {
            }
        };

        public static String byteArrayToHexString(byte[] b) {
            StringBuffer resultSb = new StringBuffer();

            for (int i = 0; i < b.length; ++i) {
                resultSb.append(byteToHexString(b[i]));
            }
            return resultSb.toString();
        }

        private static String byteToHexString(byte b) {
            int n = b;
            if (n < 0)
                n += 256;
            int d1 = n / 16;
            int d2 = n % 16;
            return hexDigits[d1] + hexDigits[d2];
        }

        public static String MD5Encoding(String origin) {
            String resultString = null;
            try {
                resultString = new String(origin);
                resultString = byteArrayToHexString(md.digest(resultString.getBytes()));
            } catch (Exception localException) {
            }
            return resultString;
        }
    }

    /**
     * Base64编码算法
     */
    static class Base64 {

        private static final int DEFAULT_BUFFER_RESIZE_FACTOR = 2;

        private static final int DEFAULT_BUFFER_SIZE = 8192;

        /**
         * Chunk size per RFC 2045 section 6.8.
         * 
         * <p>
         * The {@value} character limit does not count the trailing CRLF, but counts all other characters, including any
         * equal signs.
         * </p>
         * 
         * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 6.8</a>
         */
        static final int CHUNK_SIZE = 76;

        /**
         * Chunk separator per RFC 2045 section 2.1.
         *
         * <p>
         * N.B. The next major release may break compatibility and make this field private.
         * </p>
         * 
         * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045 section 2.1</a>
         */
        static final byte[] CHUNK_SEPARATOR = { '\r', '\n' };

        /**
         * This array is a lookup table that translates 6-bit positive integer index values into their "Base64 Alphabet"
         * equivalents as specified in Table 1 of RFC 2045.
         * 
         * Thanks to "commons" project in ws.apache.org for this code.
         * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
         */
        private static final byte[] STANDARD_ENCODE_TABLE = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' };

        /**
         * This is a copy of the STANDARD_ENCODE_TABLE above, but with + and /
         * changed to - and _ to make the encoded Base64 results more URL-SAFE.
         * This table is only used when the Base64's mode is set to URL-SAFE.
         */
        private static final byte[] URL_SAFE_ENCODE_TABLE = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_' };

        /**
         * Byte used to pad output.
         */
        private static final byte PAD = '=';

        /**
         * This array is a lookup table that translates Unicode characters drawn from the "Base64 Alphabet" (as specified in
         * Table 1 of RFC 2045) into their 6-bit positive integer equivalents. Characters that are not in the Base64
         * alphabet but fall within the bounds of the array are translated to -1.
         * 
         * Note: '+' and '-' both decode to 62. '/' and '_' both decode to 63. This means decoder seamlessly handles both
         * URL_SAFE and STANDARD base64. (The encoder, on the other hand, needs to know ahead of time what to emit).
         * 
         * Thanks to "commons" project in ws.apache.org for this code.
         * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
         */
        private static final byte[] DECODE_TABLE = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, 62, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 };

        /** Mask used to extract 6 bits, used when encoding */
        private static final int MASK_6BITS = 0x3f;

        /** Mask used to extract 8 bits, used in decoding base64 bytes */
        private static final int MASK_8BITS = 0xff;

        // The static final fields above are used for the original static byte[] methods on Base64.
        // The private member fields below are used with the new streaming approach, which requires
        // some state be preserved between calls of encode() and decode().

        /**
         * Encode table to use: either STANDARD or URL_SAFE. Note: the DECODE_TABLE above remains static because it is able
         * to decode both STANDARD and URL_SAFE streams, but the encodeTable must be a member variable so we can switch
         * between the two modes.
         */
        private final byte[] encodeTable;

        /**
         * Line length for encoding. Not used when decoding. A value of zero or less implies no chunking of the base64
         * encoded data.
         */
        private final int lineLength;

        /**
         * Line separator for encoding. Not used when decoding. Only used if lineLength > 0.
         */
        private final byte[] lineSeparator;

        /**
         * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
         * <code>decodeSize = 3 + lineSeparator.length;</code>
         */
        private final int decodeSize;

        /**
         * Convenience variable to help us determine when our buffer is going to run out of room and needs resizing.
         * <code>encodeSize = 4 + lineSeparator.length;</code>
         */
        private final int encodeSize;

        /**
         * Buffer for streaming.
         */
        private byte[] buffer;

        /**
         * Position where next character should be written in the buffer.
         */
        private int pos;

        /**
         * Position where next character should be read from the buffer.
         */
        private int readPos;

        /**
         * Variable tracks how many characters have been written to the current line. Only used when encoding. We use it to
         * make sure each encoded line never goes beyond lineLength (if lineLength > 0).
         */
        private int currentLinePos;

        /**
         * Writes to the buffer only occur after every 3 reads when encoding, an every 4 reads when decoding. This variable
         * helps track that.
         */
        private int modulus;

        /**
         * Boolean flag to indicate the EOF has been reached. Once EOF has been reached, this Base64 object becomes useless,
         * and must be thrown away.
         */
        private boolean eof;

        /**
         * Place holder for the 3 bytes we're dealing with for our base64 logic. Bitwise operations store and extract the
         * base64 encoding or decoding from this variable.
         */
        private int x;

        /**
         * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
         * <p>
         * When encoding the line length is 76, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
         * </p>
         * 
         * <p>
         * When decoding all variants are supported.
         * </p>
         */
        public Base64() {
            this(false);
        }

        /**
         * Creates a Base64 codec used for decoding (all modes) and encoding in the given URL-safe mode.
         * <p>
         * When encoding the line length is 76, the line separator is CRLF, and the encoding table is STANDARD_ENCODE_TABLE.
         * </p>
         * 
         * <p>
         * When decoding all variants are supported.
         * </p>
         * 
         * @param urlSafe
         *            if <code>true</code>, URL-safe encoding is used. In most cases this should be set to
         *            <code>false</code>.
         * @since 1.4
         */
        public Base64(boolean urlSafe) {
            this(CHUNK_SIZE, CHUNK_SEPARATOR, urlSafe);
        }

        /**
         * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
         * <p>
         * When encoding the line length is given in the constructor, the line separator is CRLF, and the encoding table is
         * STANDARD_ENCODE_TABLE.
         * </p>
         * <p>
         * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
         * </p>
         * <p>
         * When decoding all variants are supported.
         * </p>
         * 
         * @param lineLength
         *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of 4).
         *            If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.
         * @since 1.4
         */
        public Base64(int lineLength) {
            this(lineLength, CHUNK_SEPARATOR);
        }

        /**
         * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
         * <p>
         * When encoding the line length and line separator are given in the constructor, and the encoding table is
         * STANDARD_ENCODE_TABLE.
         * </p>
         * <p>
         * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
         * </p>
         * <p>
         * When decoding all variants are supported.
         * </p>
         * 
         * @param lineLength
         *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of 4).
         *            If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.
         * @param lineSeparator
         *            Each line of encoded data will end with this sequence of bytes.
         * @throws IllegalArgumentException
         *             Thrown when the provided lineSeparator included some base64 characters.
         * @since 1.4
         */
        public Base64(int lineLength, byte[] lineSeparator) {
            this(lineLength, lineSeparator, false);
        }

        /**
         * Creates a Base64 codec used for decoding (all modes) and encoding in URL-unsafe mode.
         * <p>
         * When encoding the line length and line separator are given in the constructor, and the encoding table is
         * STANDARD_ENCODE_TABLE.
         * </p>
         * <p>
         * Line lengths that aren't multiples of 4 will still essentially end up being multiples of 4 in the encoded data.
         * </p>
         * <p>
         * When decoding all variants are supported.
         * </p>
         * 
         * @param lineLength
         *            Each line of encoded data will be at most of the given length (rounded down to nearest multiple of 4).
         *            If lineLength <= 0, then the output will not be divided into lines (chunks). Ignored when decoding.
         * @param lineSeparator
         *            Each line of encoded data will end with this sequence of bytes.
         * @param urlSafe
         *            Instead of emitting '+' and '/' we emit '-' and '_' respectively. urlSafe is only applied to encode
         *            operations. Decoding seamlessly handles both modes.
         * @throws IllegalArgumentException
         *             The provided lineSeparator included some base64 characters. That's not going to work!
         * @since 1.4
         */
        public Base64(int lineLength, byte[] lineSeparator, boolean urlSafe) {
            if (lineSeparator == null) {
                lineLength = 0; // disable chunk-separating
                lineSeparator = CHUNK_SEPARATOR; // this just gets ignored
            }
            this.lineLength = lineLength > 0 ? (lineLength / 4) * 4 : 0;
            this.lineSeparator = new byte[lineSeparator.length];
            System.arraycopy(lineSeparator, 0, this.lineSeparator, 0, lineSeparator.length);
            if (lineLength > 0) {
                this.encodeSize = 4 + lineSeparator.length;
            } else {
                this.encodeSize = 4;
            }
            this.decodeSize = this.encodeSize - 1;
            if (containsBase64Byte(lineSeparator)) {
                String sep = StringCodeUtil.newStringUtf8(lineSeparator);
                throw new IllegalArgumentException("lineSeperator must not contain base64 characters: [" + sep + "]");
            }
            this.encodeTable = urlSafe ? URL_SAFE_ENCODE_TABLE : STANDARD_ENCODE_TABLE;
        }

        /**
         * Returns our current encode mode. True if we're URL-SAFE, false otherwise.
         * 
         * @return true if we're in URL-SAFE mode, false otherwise.
         * @since 1.4
         */
        public boolean isUrlSafe() {
            return this.encodeTable == URL_SAFE_ENCODE_TABLE;
        }

        /**
         * Returns true if this Base64 object has buffered data for reading.
         * 
         * @return true if there is Base64 object still available for reading.
         */
        boolean hasData() {
            return this.buffer != null;
        }

        /**
         * Returns the amount of buffered data available for reading.
         * 
         * @return The amount of buffered data available for reading.
         */
        int avail() {
            return buffer != null ? pos - readPos : 0;
        }

        /** Doubles our buffer. */
        private void resizeBuffer() {
            if (buffer == null) {
                buffer = new byte[DEFAULT_BUFFER_SIZE];
                pos = 0;
                readPos = 0;
            } else {
                byte[] b = new byte[buffer.length * DEFAULT_BUFFER_RESIZE_FACTOR];
                System.arraycopy(buffer, 0, b, 0, buffer.length);
                buffer = b;
            }
        }

        /**
         * Extracts buffered data into the provided byte[] array, starting at position bPos, up to a maximum of bAvail
         * bytes. Returns how many bytes were actually extracted.
         * 
         * @param b
         *            byte[] array to extract the buffered data into.
         * @param bPos
         *            position in byte[] array to start extraction at.
         * @param bAvail
         *            amount of bytes we're allowed to extract. We may extract fewer (if fewer are available).
         * @return The number of bytes successfully extracted into the provided byte[] array.
         */
        int readResults(byte[] b, int bPos, int bAvail) {
            if (buffer != null) {
                int len = Math.min(avail(), bAvail);
                if (buffer != b) {
                    System.arraycopy(buffer, readPos, b, bPos, len);
                    readPos += len;
                    if (readPos >= pos) {
                        buffer = null;
                    }
                } else {
                    // Re-using the original consumer's output array is only
                    // allowed for one round.
                    buffer = null;
                }
                return len;
            }
            return eof ? -1 : 0;
        }

        /**
         * Sets the streaming buffer. This is a small optimization where we try to buffer directly to the consumer's output
         * array for one round (if the consumer calls this method first) instead of starting our own buffer.
         * 
         * @param out
         *            byte[] array to buffer directly to.
         * @param outPos
         *            Position to start buffering into.
         * @param outAvail
         *            Amount of bytes available for direct buffering.
         */
        void setInitialBuffer(byte[] out, int outPos, int outAvail) {
            // We can re-use consumer's original output array under
            // special circumstances, saving on some System.arraycopy().
            if (out != null && out.length == outAvail) {
                buffer = out;
                pos = outPos;
                readPos = outPos;
            }
        }

        /**
         * <p>
         * Encodes all of the provided data, starting at inPos, for inAvail bytes. Must be called at least twice: once with
         * the data to encode, and once with inAvail set to "-1" to alert encoder that EOF has been reached, so flush last
         * remaining bytes (if not multiple of 3).
         * </p>
         * <p>
         * Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
         * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
         * </p>
         * 
         * @param in
         *            byte[] array of binary data to base64 encode.
         * @param inPos
         *            Position to start reading data from.
         * @param inAvail
         *            Amount of bytes available from input for encoding.
         */
        void encode(byte[] in, int inPos, int inAvail) {
            if (eof) {
                return;
            }
            // inAvail < 0 is how we're informed of EOF in the underlying data we're
            // encoding.
            if (inAvail < 0) {
                eof = true;
                if (buffer == null || buffer.length - pos < encodeSize) {
                    resizeBuffer();
                }
                switch (modulus) {
                    case 1:
                        buffer[pos++] = encodeTable[(x >> 2) & MASK_6BITS];
                        buffer[pos++] = encodeTable[(x << 4) & MASK_6BITS];
                        // URL-SAFE skips the padding to further reduce size.
                        if (encodeTable == STANDARD_ENCODE_TABLE) {
                            buffer[pos++] = PAD;
                            buffer[pos++] = PAD;
                        }
                        break;

                    case 2:
                        buffer[pos++] = encodeTable[(x >> 10) & MASK_6BITS];
                        buffer[pos++] = encodeTable[(x >> 4) & MASK_6BITS];
                        buffer[pos++] = encodeTable[(x << 2) & MASK_6BITS];
                        // URL-SAFE skips the padding to further reduce size.
                        if (encodeTable == STANDARD_ENCODE_TABLE) {
                            buffer[pos++] = PAD;
                        }
                        break;
                }
                if (lineLength > 0 && pos > 0) {
                    System.arraycopy(lineSeparator, 0, buffer, pos, lineSeparator.length);
                    pos += lineSeparator.length;
                }
            } else {
                for (int i = 0; i < inAvail; i++) {
                    if (buffer == null || buffer.length - pos < encodeSize) {
                        resizeBuffer();
                    }
                    modulus = (++modulus) % 3;
                    int b = in[inPos++];
                    if (b < 0) {
                        b += 256;
                    }
                    x = (x << 8) + b;
                    if (0 == modulus) {
                        buffer[pos++] = encodeTable[(x >> 18) & MASK_6BITS];
                        buffer[pos++] = encodeTable[(x >> 12) & MASK_6BITS];
                        buffer[pos++] = encodeTable[(x >> 6) & MASK_6BITS];
                        buffer[pos++] = encodeTable[x & MASK_6BITS];
                        currentLinePos += 4;
                        if (lineLength > 0 && lineLength <= currentLinePos) {
                            System.arraycopy(lineSeparator, 0, buffer, pos, lineSeparator.length);
                            pos += lineSeparator.length;
                            currentLinePos = 0;
                        }
                    }
                }
            }
        }

        /**
         * <p>
         * Decodes all of the provided data, starting at inPos, for inAvail bytes. Should be called at least twice: once
         * with the data to decode, and once with inAvail set to "-1" to alert decoder that EOF has been reached. The "-1"
         * call is not necessary when decoding, but it doesn't hurt, either.
         * </p>
         * <p>
         * Ignores all non-base64 characters. This is how chunked (e.g. 76 character) data is handled, since CR and LF are
         * silently ignored, but has implications for other bytes, too. This method subscribes to the garbage-in,
         * garbage-out philosophy: it will not check the provided data for validity.
         * </p>
         * <p>
         * Thanks to "commons" project in ws.apache.org for the bitwise operations, and general approach.
         * http://svn.apache.org/repos/asf/webservices/commons/trunk/modules/util/
         * </p>
         * 
         * @param in
         *            byte[] array of ascii data to base64 decode.
         * @param inPos
         *            Position to start reading data from.
         * @param inAvail
         *            Amount of bytes available from input for encoding.
         */
        void decode(byte[] in, int inPos, int inAvail) {
            if (eof) {
                return;
            }
            if (inAvail < 0) {
                eof = true;
            }
            for (int i = 0; i < inAvail; i++) {
                if (buffer == null || buffer.length - pos < decodeSize) {
                    resizeBuffer();
                }
                byte b = in[inPos++];
                if (b == PAD) {
                    // We're done.
                    eof = true;
                    break;
                } else {
                    if (b >= 0 && b < DECODE_TABLE.length) {
                        int result = DECODE_TABLE[b];
                        if (result >= 0) {
                            modulus = (++modulus) % 4;
                            x = (x << 6) + result;
                            if (modulus == 0) {
                                buffer[pos++] = (byte) ((x >> 16) & MASK_8BITS);
                                buffer[pos++] = (byte) ((x >> 8) & MASK_8BITS);
                                buffer[pos++] = (byte) (x & MASK_8BITS);
                            }
                        }
                    }
                }
            }

            // Two forms of EOF as far as base64 decoder is concerned: actual
            // EOF (-1) and first time '=' character is encountered in stream.
            // This approach makes the '=' padding characters completely optional.
            if (eof && modulus != 0) {
                x = x << 6;
                switch (modulus) {
                    case 2:
                        x = x << 6;
                        buffer[pos++] = (byte) ((x >> 16) & MASK_8BITS);
                        break;
                    case 3:
                        buffer[pos++] = (byte) ((x >> 16) & MASK_8BITS);
                        buffer[pos++] = (byte) ((x >> 8) & MASK_8BITS);
                        break;
                }
            }
        }

        /**
         * Returns whether or not the <code>octet</code> is in the base 64 alphabet.
         * 
         * @param octet
         *            The value to test
         * @return <code>true</code> if the value is defined in the the base 64 alphabet, <code>false</code> otherwise.
         * @since 1.4
         */
        public static boolean isBase64(byte octet) {
            return octet == PAD || (octet >= 0 && octet < DECODE_TABLE.length && DECODE_TABLE[octet] != -1);
        }

        /**
         * Tests a given byte array to see if it contains only valid characters within the Base64 alphabet. Currently the
         * method treats whitespace as valid.
         * 
         * @param arrayOctet
         *            byte array to test
         * @return <code>true</code> if all bytes are valid characters in the Base64 alphabet or if the byte array is empty;
         *         false, otherwise
         */
        public static boolean isArrayByteBase64(byte[] arrayOctet) {
            for (int i = 0; i < arrayOctet.length; i++) {
                if (!isBase64(arrayOctet[i]) && !isWhiteSpace(arrayOctet[i])) {
                    return false;
                }
            }
            return true;
        }

        /**
         * Tests a given byte array to see if it contains only valid characters within the Base64 alphabet.
         * 
         * @param arrayOctet
         *            byte array to test
         * @return <code>true</code> if any byte is a valid character in the Base64 alphabet; false herwise
         */
        private static boolean containsBase64Byte(byte[] arrayOctet) {
            for (int i = 0; i < arrayOctet.length; i++) {
                if (isBase64(arrayOctet[i])) {
                    return true;
                }
            }
            return false;
        }

        /**
         * Encodes binary data using the base64 algorithm but does not chunk the output.
         * 
         * @param binaryData
         *            binary data to encode
         * @return byte[] containing Base64 characters in their UTF-8 representation.
         */
        public static byte[] encodeBase64(byte[] binaryData) {
            return encodeBase64(binaryData, false);
        }

        /**
         * Encodes binary data using the base64 algorithm into 76 character blocks separated by CRLF.
         *
         * @param binaryData
         *            binary data to encode
         * @return String containing Base64 characters.
         * @since 1.4
         */
        public static String encodeBase64String(byte[] binaryData) {
            return StringCodeUtil.newStringUtf8(encodeBase64(binaryData, true));
        }

        /**
         * Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output. The
         * url-safe variation emits - and _ instead of + and / characters.
         * 
         * @param binaryData
         *            binary data to encode
         * @return byte[] containing Base64 characters in their UTF-8 representation.
         * @since 1.4
         */
        public static byte[] encodeBase64URLSafe(byte[] binaryData) {
            return encodeBase64(binaryData, false, true);
        }

        /**
         * Encodes binary data using a URL-safe variation of the base64 algorithm but does not chunk the output. The
         * url-safe variation emits - and _ instead of + and / characters.
         *
         * @param binaryData
         *            binary data to encode
         * @return String containing Base64 characters
         * @since 1.4
         */
        public static String encodeBase64URLSafeString(byte[] binaryData) {
            return StringCodeUtil.newStringUtf8(encodeBase64(binaryData, false, true));
        }

        /**
         * Encodes binary data using the base64 algorithm and chunks the encoded output into 76 character blocks
         * 
         * @param binaryData
         *            binary data to encode
         * @return Base64 characters chunked in 76 character blocks
         */
        public static byte[] encodeBase64Chunked(byte[] binaryData) {
            return encodeBase64(binaryData, true);
        }

        /**
         * Decodes an Object using the base64 algorithm. This method is provided in order to satisfy the requirements of the
         * Decoder interface, and will throw a DecoderException if the supplied object is not of type byte[] or String.
         * 
         * @param pObject
         *            Object to decode
         * @return An object (of type byte[]) containing the binary data which corresponds to the byte[] or String supplied.
         * @throws CodingException
         *             if the parameter supplied is not of type byte[]
         */
        public Object decode(Object pObject) throws CodingException {
            if (pObject instanceof byte[]) {
                return decode((byte[]) pObject);
            } else if (pObject instanceof String) {
                return decode((String) pObject);
            } else {
                throw new CodingException("Parameter supplied to Base64 decode is not a byte[] or a String");
            }
        }

        /**
         * Decodes a String containing containing characters in the Base64 alphabet.
         *
         * @param pArray
         *            A String containing Base64 character data
         * @return a byte array containing binary data
         * @since 1.4
         */
        public byte[] decode(String pArray) {
            return decode(StringCodeUtil.getBytesUtf8(pArray));
        }

        /**
         * Decodes a byte[] containing containing characters in the Base64 alphabet.
         * 
         * @param pArray
         *            A byte array containing Base64 character data
         * @return a byte array containing binary data
         */
        public byte[] decode(byte[] pArray) {
            reset();
            if (pArray == null || pArray.length == 0) {
                return pArray;
            }
            long len = (pArray.length * 3) / 4;
            byte[] buf = new byte[(int) len];
            setInitialBuffer(buf, 0, buf.length);
            decode(pArray, 0, pArray.length);
            decode(pArray, 0, -1); // Notify decoder of EOF.

            // Would be nice to just return buf (like we sometimes do in the encode
            // logic), but we have no idea what the line-length was (could even be
            // variable).  So we cannot determine ahead of time exactly how big an
            // array is necessary.  Hence the need to construct a 2nd byte array to
            // hold the final result:

            byte[] result = new byte[pos];
            readResults(result, 0, result.length);
            return result;
        }

        /**
         * Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
         * 
         * @param binaryData
         *            Array containing binary data to encode.
         * @param isChunked
         *            if <code>true</code> this encoder will chunk the base64 output into 76 character blocks
         * @return Base64-encoded data.
         * @throws IllegalArgumentException
         *             Thrown when the input array needs an output array bigger than {@link Integer#MAX_VALUE}
         */
        public static byte[] encodeBase64(byte[] binaryData, boolean isChunked) {
            return encodeBase64(binaryData, isChunked, false);
        }

        /**
         * Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
         * 
         * @param binaryData
         *            Array containing binary data to encode.
         * @param isChunked
         *            if <code>true</code> this encoder will chunk the base64 output into 76 character blocks
         * @param urlSafe
         *            if <code>true</code> this encoder will emit - and _ instead of the usual + and / characters.
         * @return Base64-encoded data.
         * @throws IllegalArgumentException
         *             Thrown when the input array needs an output array bigger than {@link Integer#MAX_VALUE}
         * @since 1.4
         */
        public static byte[] encodeBase64(byte[] binaryData, boolean isChunked, boolean urlSafe) {
            return encodeBase64(binaryData, isChunked, urlSafe, Integer.MAX_VALUE);
        }

        /**
         * Encodes binary data using the base64 algorithm, optionally chunking the output into 76 character blocks.
         * 
         * @param binaryData
         *            Array containing binary data to encode.
         * @param isChunked
         *            if <code>true</code> this encoder will chunk the base64 output into 76 character blocks
         * @param urlSafe
         *            if <code>true</code> this encoder will emit - and _ instead of the usual + and / characters.
         * @param maxResultSize
         *            The maximum result size to accept.
         * @return Base64-encoded data.
         * @throws IllegalArgumentException
         *             Thrown when the input array needs an output array bigger than maxResultSize
         * @since 1.4
         */
        public static byte[] encodeBase64(byte[] binaryData, boolean isChunked, boolean urlSafe, int maxResultSize) {
            if (binaryData == null || binaryData.length == 0) {
                return binaryData;
            }

            long len = getEncodeLength(binaryData, CHUNK_SIZE, CHUNK_SEPARATOR);
            if (len > maxResultSize) {
                throw new IllegalArgumentException("Input array too big, the output array would be bigger (" + len + ") than the specified maxium size of " + maxResultSize);
            }

            Base64 b64 = isChunked ? new Base64(urlSafe) : new Base64(0, CHUNK_SEPARATOR, urlSafe);
            return b64.encode(binaryData);
        }

        /**
         * Decodes a Base64 String into octets
         *
         * @param base64String
         *            String containing Base64 data
         * @return Array containing decoded data.
         * @since 1.4
         */
        public static byte[] decodeBase64(String base64String) {
            return new Base64().decode(base64String);
        }

        /**
         * Decodes Base64 data into octets
         * 
         * @param base64Data
         *            Byte array containing Base64 data
         * @return Array containing decoded data.
         */
        public static byte[] decodeBase64(byte[] base64Data) {
            return new Base64().decode(base64Data);
        }

        /**
         * Checks if a byte value is whitespace or not.
         * 
         * @param byteToCheck
         *            the byte to check
         * @return true if byte is whitespace, false otherwise
         */
        private static boolean isWhiteSpace(byte byteToCheck) {
            switch (byteToCheck) {
                case ' ':
                case '\n':
                case '\r':
                case '\t':
                    return true;
                default:
                    return false;
            }
        }

        // Implementation of the Encoder Interface

        /**
         * Encodes an Object using the base64 algorithm. This method is provided in order to satisfy the requirements of the
         * Encoder interface, and will throw an EncoderException if the supplied object is not of type byte[].
         * 
         * @param pObject
         *            Object to encode
         * @return An object (of type byte[]) containing the base64 encoded data which corresponds to the byte[] supplied.
         * @throws EncoderException
         *             if the parameter supplied is not of type byte[]
         */
        public Object encode(Object pObject) throws CodingException {
            if (!(pObject instanceof byte[])) {
                throw new CodingException("Parameter supplied to Base64 encode is not a byte[]");
            }
            return encode((byte[]) pObject);
        }

        /**
         * Encodes a byte[] containing binary data, into a String containing characters in the Base64 alphabet.
         *
         * @param pArray
         *            a byte array containing binary data
         * @return A String containing only Base64 character data
         * @since 1.4
         */
        public String encodeToString(byte[] pArray) {
            return StringCodeUtil.newStringUtf8(encode(pArray));
        }

        /**
         * Encodes a byte[] containing binary data, into a byte[] containing characters in the Base64 alphabet.
         * 
         * @param pArray
         *            a byte array containing binary data
         * @return A byte array containing only Base64 character data
         */
        public byte[] encode(byte[] pArray) {
            reset();
            if (pArray == null || pArray.length == 0) {
                return pArray;
            }
            long len = getEncodeLength(pArray, lineLength, lineSeparator);
            byte[] buf = new byte[(int) len];
            setInitialBuffer(buf, 0, buf.length);
            encode(pArray, 0, pArray.length);
            encode(pArray, 0, -1); // Notify encoder of EOF.
            // Encoder might have resized, even though it was unnecessary.
            if (buffer != buf) {
                readResults(buf, 0, buf.length);
            }
            // In URL-SAFE mode we skip the padding characters, so sometimes our
            // final length is a bit smaller.
            if (isUrlSafe() && pos < buf.length) {
                byte[] smallerBuf = new byte[pos];
                System.arraycopy(buf, 0, smallerBuf, 0, pos);
                buf = smallerBuf;
            }
            return buf;
        }

        /**
         * Pre-calculates the amount of space needed to base64-encode the supplied array.
         *
         * @param pArray byte[] array which will later be encoded
         * @param chunkSize line-length of the output (<= 0 means no chunking) between each
         *        chunkSeparator (e.g. CRLF).
         * @param chunkSeparator the sequence of bytes used to separate chunks of output (e.g. CRLF).
         *
         * @return amount of space needed to encoded the supplied array.  Returns
         *         a long since a max-len array will require Integer.MAX_VALUE + 33%.
         */
        private static long getEncodeLength(byte[] pArray, int chunkSize, byte[] chunkSeparator) {
            // base64 always encodes to multiples of 4.
            chunkSize = (chunkSize / 4) * 4;

            long len = (pArray.length * 4) / 3;
            long mod = len % 4;
            if (mod != 0) {
                len += 4 - mod;
            }
            if (chunkSize > 0) {
                boolean lenChunksPerfectly = len % chunkSize == 0;
                len += (len / chunkSize) * chunkSeparator.length;
                if (!lenChunksPerfectly) {
                    len += chunkSeparator.length;
                }
            }
            return len;
        }

        // Implementation of integer encoding used for crypto
        /**
         * Decodes a byte64-encoded integer according to crypto standards such as W3C's XML-Signature
         * 
         * @param pArray
         *            a byte array containing base64 character data
         * @return A BigInteger
         * @since 1.4
         */
        public static BigInteger decodeInteger(byte[] pArray) {
            return new BigInteger(1, decodeBase64(pArray));
        }

        /**
         * Encodes to a byte64-encoded integer according to crypto standards such as W3C's XML-Signature
         * 
         * @param bigInt
         *            a BigInteger
         * @return A byte array containing base64 character data
         * @throws NullPointerException
         *             if null is passed in
         * @since 1.4
         */
        public static byte[] encodeInteger(BigInteger bigInt) {
            if (bigInt == null) {
                throw new NullPointerException("encodeInteger called with null parameter");
            }
            return encodeBase64(toIntegerBytes(bigInt), false);
        }

        /**
         * Returns a byte-array representation of a <code>BigInteger</code> without sign bit.
         * 
         * @param bigInt
         *            <code>BigInteger</code> to be converted
         * @return a byte array representation of the BigInteger parameter
         */
        static byte[] toIntegerBytes(BigInteger bigInt) {
            int bitlen = bigInt.bitLength();
            // round bitlen
            bitlen = ((bitlen + 7) >> 3) << 3;
            byte[] bigBytes = bigInt.toByteArray();

            if (((bigInt.bitLength() % 8) != 0) && (((bigInt.bitLength() / 8) + 1) == (bitlen / 8))) {
                return bigBytes;
            }
            // set up params for copying everything but sign bit
            int startSrc = 0;
            int len = bigBytes.length;

            // if bigInt is exactly byte-aligned, just skip signbit in copy
            if ((bigInt.bitLength() % 8) == 0) {
                startSrc = 1;
                len--;
            }
            int startDst = bitlen / 8 - len; // to pad w/ nulls as per spec
            byte[] resizedBytes = new byte[bitlen / 8];
            System.arraycopy(bigBytes, startSrc, resizedBytes, startDst, len);
            return resizedBytes;
        }

        /**
         * Resets this Base64 object to its initial newly constructed state.
         */
        private void reset() {
            buffer = null;
            pos = 0;
            readPos = 0;
            currentLinePos = 0;
            modulus = 0;
            eof = false;
        }
    }

    static class Hex {

        /**
         * Used to build output as Hex
         */
        private static final char[] DIGITS_LOWER = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

        /**
         * Used to build output as Hex
         */
        private static final char[] DIGITS_UPPER = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

        /**
         * Converts an array of characters representing hexadecimal values into an array of bytes of those same values. The
         * returned array will be half the length of the passed array, as it takes two characters to represent any given
         * byte. An exception is thrown if the passed char array has an odd number of elements.
         * 
         * @param data
         *            An array of characters containing hexadecimal digits
         * @return A byte array containing binary data decoded from the supplied char array.
         * @throws DecoderException
         *             Thrown if an odd number or illegal of characters is supplied
         */
        public static byte[] decodeHex(char[] data) throws CodingException {

            int len = data.length;

            if ((len & 0x01) != 0) {
                throw new CodingException("Odd number of characters.");
            }

            byte[] out = new byte[len >> 1];

            // two characters form the hex value.
            for (int i = 0, j = 0; j < len; i++) {
                int f = toDigit(data[j], j) << 4;
                j++;
                f = f | toDigit(data[j], j);
                j++;
                out[i] = (byte) (f & 0xFF);
            }

            return out;
        }

        /**
         * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
         * The returned array will be double the length of the passed array, as it takes two characters to represent any
         * given byte.
         * 
         * @param data
         *            a byte[] to convert to Hex characters
         * @return A char[] containing hexadecimal characters
         */
        public static char[] encodeHex(byte[] data) {
            return encodeHex(data, true);
        }

        /**
         * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
         * The returned array will be double the length of the passed array, as it takes two characters to represent any
         * given byte.
         * 
         * @param data
         *            a byte[] to convert to Hex characters
         * @param toLowerCase
         *            <code>true</code> converts to lowercase, <code>false</code> to uppercase
         * @return A char[] containing hexadecimal characters
         * @since 1.4
         */
        public static char[] encodeHex(byte[] data, boolean toLowerCase) {
            return encodeHex(data, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER);
        }

        /**
         * Converts an array of bytes into an array of characters representing the hexadecimal values of each byte in order.
         * The returned array will be double the length of the passed array, as it takes two characters to represent any
         * given byte.
         * 
         * @param data
         *            a byte[] to convert to Hex characters
         * @param toDigits
         *            the output alphabet
         * @return A char[] containing hexadecimal characters
         * @since 1.4
         */
        protected static char[] encodeHex(byte[] data, char[] toDigits) {
            int l = data.length;
            char[] out = new char[l << 1];
            // two characters form the hex value.
            for (int i = 0, j = 0; i < l; i++) {
                out[j++] = toDigits[(0xF0 & data[i]) >>> 4];
                out[j++] = toDigits[0x0F & data[i]];
            }
            return out;
        }

        /**
         * Converts an array of bytes into a String representing the hexadecimal values of each byte in order. The returned
         * String will be double the length of the passed array, as it takes two characters to represent any given byte.
         * 
         * @param data
         *            a byte[] to convert to Hex characters
         * @return A String containing hexadecimal characters
         * @since 1.4
         */
        public static String encodeHexString(byte[] data) {
            return new String(encodeHex(data));
        }

        /**
         * Converts a hexadecimal character to an integer.
         * 
         * @param ch
         *            A character to convert to an integer digit
         * @param index
         *            The index of the character in the source
         * @return An integer
         * @throws DecoderException
         *             Thrown if ch is an illegal hex character
         */
        protected static int toDigit(char ch, int index) throws CodingException {
            int digit = Character.digit(ch, 16);
            if (digit == -1) {
                throw new CodingException("Illegal hexadecimal charcter " + ch + " at index " + index);
            }
            return digit;
        }

        private final String charsetName;

        public Hex() {
            this.charsetName = UTF8;
        }

        /**
         * Creates a new codec with the given charset name.
         * 
         * @param csName
         *            the charset name.
         * @since 1.4
         */
        public Hex(String csName) {
            this.charsetName = csName;
        }

        /**
         * Converts an array of character bytes representing hexadecimal values into an array of bytes of those same values.
         * The returned array will be half the length of the passed array, as it takes two characters to represent any given
         * byte. An exception is thrown if the passed char array has an odd number of elements.
         * 
         * @param array
         *            An array of character bytes containing hexadecimal digits
         * @return A byte array containing binary data decoded from the supplied byte array (representing characters).
         * @throws DecoderException
         *             Thrown if an odd number of characters is supplied to this function
         * @see #decodeHex(char[])
         */
        public byte[] decode(byte[] array) throws CodingException {
            try {
                return decodeHex(new String(array, getCharsetName()).toCharArray());
            } catch (UnsupportedEncodingException e) {
                throw new CodingException(e.getMessage(), e);
            }
        }

        /**
         * Converts a String or an array of character bytes representing hexadecimal values into an array of bytes of those
         * same values. The returned array will be half the length of the passed String or array, as it takes two characters
         * to represent any given byte. An exception is thrown if the passed char array has an odd number of elements.
         * 
         * @param object
         *            A String or, an array of character bytes containing hexadecimal digits
         * @return A byte array containing binary data decoded from the supplied byte array (representing characters).
         * @throws DecoderException
         *             Thrown if an odd number of characters is supplied to this function or the object is not a String or
         *             char[]
         * @see #decodeHex(char[])
         */
        public Object decode(Object object) throws CodingException {
            try {
                char[] charArray = object instanceof String ? ((String) object).toCharArray() : (char[]) object;
                return decodeHex(charArray);
            } catch (ClassCastException e) {
                throw new CodingException(e.getMessage(), e);
            }
        }

        /**
         * Converts an array of bytes into an array of bytes for the characters representing the hexadecimal values of each
         * byte in order. The returned array will be double the length of the passed array, as it takes two characters to
         * represent any given byte.
         * <p>
         * The conversion from hexadecimal characters to the returned bytes is performed with the charset named by
         * {@link #getCharsetName()}.
         * </p>
         * 
         * @param array
         *            a byte[] to convert to Hex characters
         * @return A byte[] containing the bytes of the hexadecimal characters
         * @throws IllegalStateException
         *             if the charsetName is invalid. This API throws {@link IllegalStateException} instead of
         *             {@link UnsupportedEncodingException} for backward compatibility.
         * @see #encodeHex(byte[])
         */
        public byte[] encode(byte[] array) {
            return StringCodeUtil.getBytesUnchecked(encodeHexString(array), getCharsetName());
        }

        /**
         * Converts a String or an array of bytes into an array of characters representing the hexadecimal values of each
         * byte in order. The returned array will be double the length of the passed String or array, as it takes two
         * characters to represent any given byte.
         * <p>
         * The conversion from hexadecimal characters to bytes to be encoded to performed with the charset named by
         * {@link #getCharsetName()}.
         * </p>
         * 
         * @param object
         *            a String, or byte[] to convert to Hex characters
         * @return A char[] containing hexadecimal characters
         * @throws EncoderException
         *             Thrown if the given object is not a String or byte[]
         * @see #encodeHex(byte[])
         */
        public Object encode(Object object) throws CodingException {
            try {
                byte[] byteArray = object instanceof String ? ((String) object).getBytes(getCharsetName()) : (byte[]) object;
                return encodeHex(byteArray);
            } catch (ClassCastException e) {
                throw new CodingException(e.getMessage(), e);
            } catch (UnsupportedEncodingException e) {
                throw new CodingException(e.getMessage(), e);
            }
        }

        /**
         * Gets the charset name.
         * 
         * @return the charset name.
         * @since 1.4
         */
        public String getCharsetName() {
            return this.charsetName;
        }

        /**
         * Returns a string representation of the object, which includes the charset name.
         * 
         * @return a string representation of the object.
         */
        public String toString() {
            return super.toString() + "[charsetName=" + this.charsetName + "]";
        }
    }
}
